package bishi.wangyi;

import java.util.Scanner;

/**
 * @Classname Main1
 * @Description TODO
 * @Date 2021/9/19 15:27
 * @Created by ASUS
 */
public class Main1 {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        scanner.nextLine();
        String s = scanner.nextLine();
        int red = 0, blue = 0;
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) == 'B') blue++;
            else red++;
        }
        System.out.println(Math.min(red, blue) + 1);
    }
}
